How to correctly unwrap complex shapes
Final result:



Overview:

First of all you need to clean up this mesh to have only quad faces, without it this method won't work. This is a good practice and this is a proper topology. That will allow you to use modifiers, better UVs, animations etc.




Next you will need to Mark Seam in a place which wouldn't be seen much (back of the hand, or near the body).
After that select all and Unwrap the mesh.
Select one face and straighten it in UV Image Editor (W > Align Auto - two vertices at a time).
Again select whole mesh an Unwrap > Follow Active Quad.